Barbara-
The free demo version that I have only opens .jpg files (and only alows you to save the results as .jpg--suffering another quality loss). I think that the version that you can get now also opens/saves .TIFF(?), but in neither case does it deal with .PSD formats. I don't think this limitation is in the commercial version--and I think that one of the $$ versions has a PS plug-in.

I have had good results cleaning up (salvaging) some of my U20 images--no option but .jpg--but haven't found the need yet to go beyond the demo version and get a 'production' noise reduction program.

I've read that Noise Ninja is the top pick today.

BTW, wouldn't you want to do the noise filter pass as the very first step of your work flow--before you saved as .PSD?

The one you pay for (it isn't that expensive) has a PS plugin for the PC. I assume it works on one layer. So you'd convert from raw, run Neat Image's plugin and then continue with your workflow. I believe this would give you want you want.

others...

Last I read, neatimage was the best noise reduction package out there. This was done in a comparison of about... 10 packages, some costing loads of money. Maybe noiseninja wasn't in that review? I looked around in my links, but couldn't find the review.

Personally, when used correctly Neat Image does everything I could ask in noise reduction. When I switch to shooting RAW, I expect I'll buy the pro version to get the plugin. Personally, the extra jpg compression pass hasn't hurt my stuff enough that it's been worth buying the pro version yet.

The one you pay for (it isn't that expensive) has a PS plugin for the PC. I assume it works on one layer. So you'd convert from raw, run Neat Image's plugin and then continue with your workflow. I believe this would give you want you want.

The following doesn't cover the situation with NeatImage at all, but it reminded me of a favorite rant:

I consistently reject software after downloading demos that are crippled enough that I can't evaluate their qualities. Recently, I downloaded a demo from Extensis, and when I found it wouldn't let me test the filters on my own images--only their specially chosen ones--I promptly uninstalled the demo. Their filters are far too expensive to buy blindly. It's okay if the save function is crippled, but when you can't fully test the capabilities, I'm off and gone to another vendor. I won't buy shoes without trying them on and walking a bit in them. Same goes for software.

Although I haven't needed to use NI a lot, I'll align with Eric S. I quickly upgraded to the pro version for the PS plugin functionality and ability to use on uncompressed formats. It can also be included in PS Actions.

Unless I'm mistaken, I've always assumed that the NI PS plugin should be input file format agnostic, since it works on the decompressed or raw bitmap in memory, after the image imports into PS. - so NI isn't actually doing anything with the input file - PS is doing that.

My pro version with PS plugin, read a TIFF or png file opened in PS fine, you just need a fast cpu in your PC for big Mpix!! VOX